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(Click for frequent words.) 66 planets 66 innermost planet 64 icy moons 64 Solar System 63 Pluto Charon 63 Jupiter Saturn 63 Comet #P/Churyumov-Gerasimenko 62 Oort cloud 62 Kuiper belt objects 62 planets orbits 61 comets 61 ringed planet 61 gaseous planet 61 Cosmic Microwave Background 61 Churyumov Gerasimenko 61 Saturn moons 61 Voyager spacecraft 61 Kuiper Belt Objects 61 Kuiper belt 60 Oort Cloud 60 Upsilon Andromedae 60 Jovian moons 60 twin Voyager spacecraft 60 extrasolar 60 exoplanets planets 60 Saturn rings 60 KBOs 60 Galilean moons 60 exoplanetary 60 planet Uranus 60 comets asteroids 60 planets Uranus 60 Cassini Huygens 60 comet Churyumov Gerasimenko 60 comet nucleus 60 Earthlike planets 59 distant galaxies 59 Saturn Cassini 59 Milky Way Galaxy 59 icy comets 59 inhabitable planets 59 astrophysical phenomena 59 Jupiter Saturn Uranus 59 exo planets 59 WASP #b 59 Comet Halley 59 comets orbiting 59 planets orbiting stars 59 protoplanet 59 circular orbits 58 rovers Spirit 58 planets moons 58 ecliptic plane 58 terrestrial planets 58 Epsilon Eridani 58 outermost planets 58 Comet Hartley 2 58 cosmos 58 Comet Churyumov Gerasimenko 58 exoplanets orbiting 58 interstellar 58 Nasa spacecraft 58 asteroids 58 Kuiper Belt 58 Uranus 58 planetary 58 moon Charon 58 elliptical orbits 58 retrograde orbit 58 sunlike star 58 planets comets 58 Mars rovers Spirit 57 spacecraft 57 planemos 57 comet 57 unmanned probes 57 Galileo spacecraft 57 galaxy 57 orbits 57 COROT 57 galactic cosmic rays 57 Venusian atmosphere 57 coronal mass ejections CMEs 57 extrasolar planets 57 interstellar dust 57 planetesimals 57 New Horizons spacecraft 57 nebular 57 asteroid Vesta 57 Milky Way galaxy 57 Solar TErrestrial RElations Observatory 57 jovian 57 protoplanets 57 Corot 7b 57 interstellar particles 57 extrasolar planetary systems 57 exoplanets 57 Comet Hartley 57 NASA rovers Spirit 57 gaseous planets 57 supernova explosions 57 Saturnian system 57 Gravitational waves 57 Antennae Galaxies 57 planetary nebulae 57 interstellar space 57 coronal loops 56 Earth magnetosphere 56 moons 56 solar nebula 56 galaxies 56 supernovae 56 moons orbiting 56 Voyager probes 56 asteroid belt 56 moons Phobos 56 circumstellar disks 56 Saturnian 56 Galaxy Evolution 56 Halley comet 56 orbiting 56 Mars moon Phobos 56 retrograde orbits 56 Galilean satellites 56 Sojourner rover 56 Jupiter icy moons 56 cometary 56 highly elliptical orbits 56 lunar perigee 56 supernova explosion 56 moons circling 56 Kuiper Belt objects 56 accretion disks 56 Pluto Eris 56 planetoids 56 Ranging spacecraft 56 Manned missions 56 observable universe 56 moon Ganymede 56 orbited Jupiter 56 Kuiper Belt Object 56 exosolar planets 56 magnetosphere 56 Saturnian moon 56 planet magnetosphere 56 cosmic rays 56 moon Io 56 Cassini 56 spacecrafts 56 #P/Churyumov-Gerasimenko 56 Pluto 56 Beta Pictoris b 56 Galactic cosmic rays 55 reionization 55 Mars 55 Mandushev 55 celestial bodies 55 comet Wild 55 CoRoT 9b 55 prograde 55 Saturnian moon Titan 55 Hot Jupiters 55 planets orbiting 55 asteroidal 55 Hale Bopp 55 coronal mass ejections 55 colliding galaxies 55 GJ #b [001] 55 cosmic ray 55 occultations 55 globular clusters 55 SIRTF 55 alien civilizations 55 BepiColombo 55 Martian surface 55 cosmic 55 solar corona 55 impactors 55 cosmic microwave background 55 orbiting Hubble Space Telescope 55 Red Planet 55 detect gravitational waves 55 interplanetary spacecraft 55 Andromeda Galaxy 55 exoplanets planets outside 55 rocky planets 55 Toutatis 55 sized planets orbiting 55 martian 55 asteroid 55 distant supernovae 55 Wilkinson Microwave Anisotropy Probe 55 hot Jupiters 55 heliopause 55 moon Europa 55 NASA STEREO 54 planets asteroids 54 Carina constellation 54 Kuiper Belt object 54 interstellar medium 54 Saturn Uranus 54 magnetotail 54 robotic explorer 54 planets orbiting distant 54 P/# A2 54 robotic rovers 54 exo planet 54 Saturn moon 54 planetary orbits 54 planetary embryos 54 TrES 4 54 BP Psc 54 Cepheid variables 54 elliptical galaxies 54 magnetospheric 54 Wolszczan 54 celestial sphere 54 Zeta Ophiuchi 54 noctilucent clouds 54 orbiting observatory 54 JIMO 54 super Earths 54 interplanetary 54 planetary Transits 54 planetary surfaces 54 Hubble Space Telescope 54 Cassini Huygens spacecraft 54 Trojan asteroids 54 sunlike stars 54 WISE spacecraft 54 Planck satellite 54 extrasolar planets orbiting 54 galaxy formation 54 orbiting observatories 54 meteoroid impacts 54 protoplanetary disk 54 magnetars 54 galactic 54 Kepler 9c 54 Itokawa asteroid 54 Andromeda galaxy 54 asteroids comets 54 dwarf galaxies 54 dirty snowballs 54 perihelion 54 NASA Cassini 54 phyllosilicates 54 STEREO spacecraft 54 heliospheric 54 lunar crust 54 galactic disk 54 habitable planets 54 gravitational interactions 54 lunar landers 54 NASA Voyager spacecraft 54 Alpha Centauri 54 lunar surface 54 elongated orbits 54 habitable planet 54 heliosphere 54 gravitational lenses 54 plutoids 54 photosphere 54 HD#b 54 Rosetta spacecraft 53 Mars rovers 53 Earth orbit 53 Phobos 53 Jovian moon 53 Mars landers 53 planets orbiting sun 53 ejecta 53 active galactic nuclei 53 Orion Nebula 53 Comet Tempel 1 53 interstellar dust grains 53 spacecraft flyby 53 NASA MESSENGER spacecraft 53 distant supernovas 53 Io Europa 53 magnetic reconnection 53 Ulysses spacecraft 53 comets meteors 53 NASA Stardust spacecraft 53 Gamma ray bursts 53 neutralinos 53 infalling 53 comet #P/Churyumov-Gerasimenko 53 distant quasars 53 NuSTAR 53 nebulae 53 HD #b [002] 53 Cancri e 53 robotic explorers 53 astrophysical 53 Fomalhaut b 53 Hubble Telescope 53 Viking landers 53 Relations Observatory STEREO 53 Solar Dynamics Observatory 53 Olympus Mons 53 millisecond pulsars 53 earthlike planets 53 planets circling stars 53 fainter objects 53 distant galaxy 53 galaxy M# [001] 53 Deep Impact eXtended Investigation 53 Magellanic Clouds 53 binary asteroid 53 orbital rendezvous 53 Martian atmosphere 53 highly elliptical orbit 53 trans Neptunian objects 53 Lunar Reconnaissance Orbiter LRO 53 NASA rovers 53 MARSIS radar 53 robotic spacecraft 53 proto galaxies 53 brown dwarfs 53 protostars 53 spacecraft Cassini 53 merging galaxies 53 MESSENGER 53 Virgo Cluster 53 periodic dimming 53 martian atmosphere 53 Jupiter flyby 53 orbiters 53 orbiting Mars 53 Stardust spacecraft 53 lobate scarps 53 planetary atmospheres 53 orbiting Saturn 53 Geminga 53 Jupiter moon Io 53 ray Space Telescope 53 Mars Phobos 53 outer space 53 permanently shadowed craters 53 Venusian 53 hypervelocity stars 53 Comet Machholz 53 orbiting telescope 53 Martian crater 53 Comet Tempel Tuttle 53 gravitational tides 53 supermassive 53 meteor impacts 53 Goldilocks planet 53 rover Opportunity 53 lunar equator 53 Lunar Prospector 52 planet WASP #b 52 EPOXI 52 crewed spacecraft 52 Cosmic Background Explorer 52 robot rovers 52 Mars Pathfinder 52 protoplanetary disks 52 planet HD #b 52 orbiting planets 52 comet Lulin 52 X ray binary 52 quasars 52 robotic probes 52 Eta Carinae 52 cosmic cannibal 52 MARSIS 52 lensing galaxy 52 interplanetary missions 52 Earth asteroids 52 cosmic phenomena 52 orbital 52 Kepler Mission 52 globulars 52 Cometary 52 Earthlike planet 52 asteroids Ceres 52 eccentric orbits 52 Evolution Explorer 52 gravitational waves 52 Interstellar Boundary Explorer 52 meteoroids 52 Comet Lulin 52 interstellar boundary 52 Stardust NExT 52 Huygens mission 52 Martian dust 52 luminous galaxies 52 Cosmic rays 52 Halley Comet 52 Gliese #e 52 astronomers 52 asteroid Steins 52 Enceladus 52 OGLE TR #b 52 planets circling 52 celestial observations 52 X ray telescopes 52 Alycia Weinberger 52 interstellar clouds 52 Gliese #c 52 Earth 52 millisecond pulsar 52 ESA Mars 52 Neutron stars 52 supernovas 52 rovers 52 protoplanetary 52 Martian plains 52 energetic electrons 52 comet Tempel Tuttle 52 Alfven waves 52 NASA MESSENGER 52 ULIRGs 52 IBEX spacecraft 52 Perseus Cluster 52 galactic halo 52 Hubble 52 NASA Cassini spacecraft 52 Itokawa 52 astrobiological 52 Mimas 52 GALEX 52 neutrinos 52 Gamma rays 52 Opportunity rovers 52 Martian craters 52 Martian 52 planetary missions 52 Cassini flyby 52 Proxima Centauri 52 astrophysical objects 52 faraway galaxies 52 cosmic ray particles 52 Opportunity rover 52 HM Cancri 52 planetoid 52 interstellar cloud 52 Hubble telescope 52 LADEE 52 exosphere 52 Space ENvironment GEochemistry 52 Jupiter Icy Moons 52 Upsilon Andromedae b 52 solar flares 52 Martian terrain 52 Kepler Space Telescope 52 frozen sunless 51 radial velocity 51 Hubble Space Telescope HST 51 blue supergiant 51 AGNs 51 GJ#b 51 Earthlike 51 transiting planet 51 twin rover Spirit 51 Enceladus flybys 51 CMEs 51 asteroid Itokawa 51 ESA Rosetta 51 magnetar 51 cosmological distances 51 CoRoT satellite 51 galactic cores 51 asteroids orbiting 51 Pluto Kuiper Belt 51 supernovae explosions 51 Solar Orbiter 51 Late Heavy Bombardment 51 THEMIS satellites 51 dynamical evolution 51 Ed Weiler NASA 51 outer corona 51 reionization epoch 51 starburst galaxy 51 substorms 51 Compton Gamma Ray 51 Jupiter Ganymede 51 Saturn magnetosphere 51 Martian equator 51 spiral galaxies 51 substorm 51 Uranus Neptune 51 habitable zones 51 GRBs 51 Bok globules 51 gravitational perturbations 51 interstellar dust clouds 51 asteroid Eros 51 HL Tau 51 Jupiter moons 51 Krimigis 51 LightSail 1 51 Rosetta comet chaser 51 OSIRIS REx 51 Ringed Planet 51 Muons 51 Kepler #b 51 Endurance crater 51 potentially habitable planets 51 Exoplanets 51 NASA twin rovers 51 martian surface 51 supersymmetric particles 51 gravitational keyhole 51 galactic magnetic 51 infrared telescopes 51 NASA THEMIS 51 Orion nebula 51 ion propulsion 51 moon Titan 51 CALIPSO 51 axions 51 flyby spacecraft 51 Linda Spilker Cassini 51 flyby Cassini 51 Epsilon Aurigae 51 gravitational tugs 51 gamma rays 51 Tempel 1 51 Epoxi 51 stellar occultations 51 Messenger spacecraft 51 particle colliders 51 mu Arae 51 NEAs 51 WMAP satellite 51 cometary debris 51 elongated orbit 51 planet Gliese #g 51 cosmic particles 51 meteorite impacts 51 Terrestrial Planet Finder 51 lunar orbits 51 Jupiter magnetosphere 51 Apollo missions 51 orbital resonance 51 extrasolar planet 51 red supergiant 51 supermassive black holes 51 Planck spacecraft 51 heavily cratered 51 Martian rovers 51 Deep Impact Extended 51 moon Mimas 51 solar minima 51 XO 3b 51 giant gaseous planets 51 proto planetary disk 51 subsurface ocean 51 infrared wavelengths 51 Ring Nebula 51 particle beam 51 exoplanet 51 asteroid Lutetia 51 radial velocity technique 51 Victoria Crater 51 planetary nebula 51 moon Mab 51 Curiosity rover 51 neutron star 51 Kuiper belt object 51 X ray observatory 51 transiting planets 51 Earth radii 51 accretion disk 51 Mars Pathfinder lander 51 extraterrestrial civilizations 50 Henize #-# 50 galactic collisions 50 Bug Nebula 50 gamma ray emission 50 Comet Elenin 50 spacetime 50 GLAST 50 planets astronomers 50 planet orbits 50 gravitational interaction 50 Corot 9b 50 SIM PlanetQuest 50 chondrules 50 galaxy clusters 50 flybys 50 aurorae 50 EPOXI mission 50 binary asteroids 50 GEochemistry 50 orbiting spacecraft 50 Explorer WISE 50 Fermi Telescope 50 Saturnian moons 50 comet dust 50 mantle plumes 50 ionosphere 50 Martian meteorites 50 extragalactic 50 Mercury flyby 50 Reconnaissance Orbiter 50 Stephan Quintet 50 gamma ray observatory 50 constellation Hercules 50 Cygnus Lyra region 50 Exoplanet 50 circumstellar 50 Hubble Space telescope 50 Comet 9P/Tempel 1 50 constellation Ursa Major 50 SN#A 50 moons Io 50 Martian arctic 50 exoplanetary systems 50 moon Enceladus 50 XMM Newton 50 Valles Marineris 50 SOHO spacecraft 50 X ray wavelengths 50 HIP #b 50 celestial objects 50 mesosphere 50 muon neutrino 50 pulsar 50 orbit 50 MErcury Surface Space ENvironment 50 planet 50 Cosmic Microwave Background CMB 50 transiting exoplanet 50 DISR 50 Emily Lakdawalla 50 pulsars 50 constellation Eridanus 50 extrasolar worlds 50 gravitationally 50 Heliospheric Observatory SOHO 50 celestial 50 antineutrinos 50 Extrasolar Planet Search 50 celestial mechanics 50 ESA Integral 50 elliptical orbit 50 redshifted 50 Comet Boethin 50 DIXI 50 chromosphere 50 NASA Kepler spacecraft 50 matter antimatter asymmetry 50 meteoroid 50 Coma Cluster 50 constellation Virgo 50 Trapezium 50 Omega Centauri 50 Global Surveyor 50 neutrino 50 comet tail 50 Endeavour Crater 50 largest moon Charon 50 interstellar grains 50 globular star 50 filamentary structure 50 Hipparcos 50 planetary science 50 Saturn Enceladus 50 Iapetus 50 Pleiades cluster 50 cosmic collisions 50 unmanned spacecraft 50 nebulas 50 Cassini Equinox 50 Substorms 50 Nibiru 50 constellation Carina 50 habitable worlds 50 Milky Way 50 gravitational microlensing 50 inner asteroid belt 50 NASA Cosmic Background 50 Observatory STEREO 50 celestial object 50 Pluto moon Charon 50 starburst galaxies 50 quark gluon plasma 50 colliding asteroids 50 neutron stars 50 Charon Pluto 50 GLAST telescope 50 Mars Odyssey spacecraft 50 X ray observatories 50 MESSENGER spacecraft 50 Fermi telescope 50 orbiting gamma ray 50 GOCE 50 Viking orbiters 50 Herschel Space 50 Gliese #d 50 Grillmair 50 Maunder minimum 50 silicon monoxide 50 Characterization EPOCh 50 Gerard Kuiper 50 moons orbiting Saturn 50 Samuel Oschin Telescope 50 sols 50 blue straggler 50 Jupiter gravitational pull 50 Sedna 50 planets atmospheres 49 lunar orbiters 49 CoRoT #b 49 Viking Lander 49 asteroid Ceres 49 Jupiter Uranus 49 Ranging MESSENGER spacecraft 49 ESA Huygens probe 49 supernova 49 heliosheath 49 manned lunar missions 49 moon Phobos 49 Vourlidas 49 exoplanet orbiting 49 gravitational wave 49 comet flyby 49 magma ocean 49 MG J# +# 49 GRB #B 49 nucleosynthesis 49 SMBHs 49 celestial phenomena 49 dwarf galaxy 49 Astrological lore 49 Pleiades star 49 X ray emission 49 Asteroid Belt 49 Huygens 49 lunar craters 49 galactic mergers 49 Orbiter MRO 49 supergiant star 49 type Ia supernovae 49 energetic cosmic rays 49 eclipsing binaries 49 Europa Ganymede 49 NASA MErcury Surface 49 helium atoms 49 Martian moons Phobos 49 auroral displays 49 Goldilocks zone 49 CoRoT 7b 49 IKAROS 49 planetary alignments 49 AB Aurigae 49 STEREO 49 red supergiants 49 Shoemaker Levy 49 gamma ray bursts 49 Neptune Uranus 49 Mars CRISM 49 Investigation DIXI 49 globular cluster 49 Yinghuo 1 49 particle detectors 49 Earth ionosphere 49 submillimeter galaxies 49 spacecraft orbiting 49 RS Ophiuchi 49 outermost planet 49 planet Nibiru 49 SDSS II 49 NASAs 49 NASA Solar Terrestrial 49 Pluto demotion 49 proplyds 49 orbiter 49 Wolf Rayet stars 49 slender crescent 49 equatorial regions 49 NASA Interstellar Boundary 49 undersea volcanoes 49 interstellar dust samples 49 stellar occultation 49 constellation Cassiopeia 49 astronomical objects 49 aphelion 49 galaxy M# [002] 49 galaxy cluster 49 HD #b [001] 49 subatomic particles 49 optical wavelengths 49 SPICAM 49 telescopic observations 49 MAVEN 49 supernovae explode 49 TNOs 49 NASA Fermi Gamma 49 swingby 49 landers 49 orbital inclination 49 Adam Riess 49 Europa Orbiter 49 Bruce Jakosky 49 gravitational pulls 49 Orionids 49 star Gliese 49 protostar 49 Huygens lander 49 infall 49 crewed missions 49 SN #A 49 JWST 49 quark gluon 49 gravitationally bound 49 COBE satellite 49 LRO spacecraft 49 twin rovers Spirit 49 Cosmic Evolution 49 particle acceleration 49 robotic geologists 49 circular orbit 49 occulted 49 Saturn moon Enceladus 49 ESA Planck 49 APXS 49 BepiColombo mission 49 Astronomers 49 Astrophysical 49 proto planetary disks 49 Cassini spacecraft 49 supervolcanoes 49 Heliophysics 49 Mojzsis 49 LCROSS mission 49 masers 49 solar neutrinos 49 lander 49 proto cluster 49 astrobiologists 49 Haumea 49 asteroid impacts 49 spacefaring 49 quasar 49 COROT exo 3b 49 astronomical phenomena 49 cosmic gamma rays 49 Cepheids 49 Eagle Nebula 49 Hubble astronomers 49 Yarkovsky effect 49 UCO Lick 49 Gravity Probe B 49 zodiacal light 49 cosmological theories 49 planet Gliese #c 49 Arches Cluster 49 moonlets 48 trans Neptunian 48 polar regions 48 sterile neutrino 48 cosmologists 48 Sasselov 48 Kailash Sahu 48 SN #C 48 Planck 48 SN #gy 48 IceCube 48 orbital velocity 48 Bose Einstein condensates 48 gamma ray burst 48 baryon 48 Giovanni Cassini 48 CMB radiation 48 occultation 48 gamma ray photons 48 extrasolar planetary 48 journal Meteoritics 48 Antenna LISA 48 orbital insertion 48 micrometeoroids 48 magnetic monopoles 48 smallest exoplanet 48 moon 48 chondrites 48 Polar Regions 48 rotational axis 48 planetary nebulas 48 Phoebe orbits 48 gamma ray flares 48 constellation Andromeda 48 Venusian surface 48 Hubble Constant 48 Mössbauer 48 neighboring Andromeda galaxy 48 Mars rover 48 Quaoar 48 axial tilt 48 stellar seismology 48 Mini TES 48 Meridiani 48 Shackleton crater 48 spatially resolved 48 ionized particles 48 galactic clusters 48 universe 48 Valles Marineris canyon 48 stellar nurseries 48 NASA Kepler 48 spinning neutron stars 48 orbiter lander 48 electron neutrinos 48 constellation Aquarius 48 Orbiter LRO 48 blazar 48 Hellas Basin 48 zodiac constellations 48 Project Ozma 48 satellites orbiting Earth 48 Helix Nebula 48 intrinsic brightness 48 spiral nebulae 48 dwarf spheroidal 48 impactor 48 rover Spirit 48 VY Canis Majoris 48 Kepler spacecraft 48 Sagittarius dwarf galaxy 48 manned lunar 48 supernova remnants 48 Isidis Planitia 48 spiral galaxy 48 Triangulum 48 lunar regolith 48 cometary dust 48 Rosetta orbiter 48 Tempel Tuttle 48 buckypaper virtually 48 Stardust NExT mission 48 asteroid collisions 48 Cloud Aerosol Lidar 48 lunar orbit 48 Comet Hale Bopp 48 JDEM 48 Astrophysics MOA 48 STEREO mission 48 pericentre 48 star Proxima Centauri 48 Shepherding Spacecraft 48 constellation Sagittarius 48 Laser Interferometer Gravitational Wave 48 dwarf spheroidal galaxies 48 polar craters 48 Descent Imager Spectral Radiometer 48 lunar meteorites 48 Titan Saturn 48 heliocentric 48 Planetary Transits 48 origins spectrograph 48 volcanic moon Io 48 GJ #b [002] 48 potentially habitable 48 nucleon 48 HD# [002] 48 sodium atoms 48 hydroxyl molecules 48 Comet McNaught 48 cosmological 48 Beta Pictoris 48 RXTE 48 Titan flyby 48 reentry capsule 48 amateur skywatchers 48 NASA rover Spirit 48 gravitational 48 Crab Nebula 48 protons 48 moons Europa 48 J# +# [002] 48 Titan smoggy 48 Nili Fossae 48 Mars Reconnaissance Orbiter 48 tidal bulge 48 robotic lander 48 ultraviolet wavelengths 48 Milky Way halo 48 extraterrestrial civilization 48 Mercury Uranus 48 outer reaches 48 Venus transits 48 antimatter particles 48 polar orbits 48 metallicity 48 observing satellites 48 EPOCh 48 primordial ingredients 48 EPOXI spacecraft 48 Laser Interferometer Space 48 Clyde Tombaugh discovered 48 Convection Rotation 48 durable twin rovers 48 Magnetars 48 supermassive black hole